1 /* 2 * Copyright (C) 2007 Red Hat. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19 #include <linux/init.h> 20 #include <linux/fs.h> 21 #include <linux/slab.h> 22 #include <linux/rwsem.h> 23 #include <linux/xattr.h> 24 #include <linux/security.h> 25 #include "ctree.h" 26 #include "btrfs_inode.h" 27 #include "transaction.h" 28 #include "xattr.h" 29 #include "disk-io.h" 30 31 32 ssize_t __btrfs_getxattr(struct inode *inode, const char *name, 33 void *buffer, size_t size) 34 { 35 struct btrfs_dir_item *di; 36 struct btrfs_root *root = BTRFS_I(inode)->root; 37 struct btrfs_path *path; 38 struct extent_buffer *leaf; 39 int ret = 0; 40 unsigned long data_ptr; 41 42 path = btrfs_alloc_path(); 43 if (!path) 44 return -ENOMEM; 45 46 /* lookup the xattr by name */ 47 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name, 48 strlen(name), 0); 49 if (!di) { 50 ret = -ENODATA; 51 goto out; 52 } else if (IS_ERR(di)) { 53 ret = PTR_ERR(di); 54 goto out; 55 } 56 57 leaf = path->nodes[0]; 58 /* if size is 0, that means we want the size of the attr */ 59 if (!size) { 60 ret = btrfs_dir_data_len(leaf, di); 61 goto out; 62 } 63 64 /* now get the data out of our dir_item */ 65 if (btrfs_dir_data_len(leaf, di) > size) { 66 ret = -ERANGE; 67 goto out; 68 } 69 70 /* 71 * The way things are packed into the leaf is like this 72 * |struct btrfs_dir_item|name|data| 73 * where name is the xattr name, so security.foo, and data is the 74 * content of the xattr. data_ptr points to the location in memory 75 * where the data starts in the in memory leaf 76 */ 77 data_ptr = (unsigned long)((char *)(di + 1) + 78 btrfs_dir_name_len(leaf, di)); 79 read_extent_buffer(leaf, buffer, data_ptr, 80 btrfs_dir_data_len(leaf, di)); 81 ret = btrfs_dir_data_len(leaf, di); 82 83 out: 84 btrfs_free_path(path); 85 return ret; 86 } 87 88 static int do_setxattr(struct btrfs_trans_handle *trans, 89 struct inode *inode, const char *name, 90 const void *value, size_t size, int flags) 91 { 92 struct btrfs_dir_item *di; 93 struct btrfs_root *root = BTRFS_I(inode)->root; 94 struct btrfs_path *path; 95 size_t name_len = strlen(name); 96 int ret = 0; 97 98 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root)) 99 return -ENOSPC; 100 101 path = btrfs_alloc_path(); 102 if (!path) 103 return -ENOMEM; 104 105 if (flags & XATTR_REPLACE) { 106 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name, 107 name_len, -1); 108 if (IS_ERR(di)) { 109 ret = PTR_ERR(di); 110 goto out; 111 } else if (!di) { 112 ret = -ENODATA; 113 goto out; 114 } 115 ret = btrfs_delete_one_dir_name(trans, root, path, di); 116 if (ret) 117 goto out; 118 btrfs_release_path(path); 119 120 /* 121 * remove the attribute 122 */ 123 if (!value) 124 goto out; 125 } 126 127 again: 128 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode), 129 name, name_len, value, size); 130 if (ret == -EEXIST) { 131 if (flags & XATTR_CREATE) 132 goto out; 133 /* 134 * We can't use the path we already have since we won't have the 135 * proper locking for a delete, so release the path and 136 * re-lookup to delete the thing. 137 */ 138 btrfs_release_path(path); 139 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), 140 name, name_len, -1); 141 if (IS_ERR(di)) { 142 ret = PTR_ERR(di); 143 goto out; 144 } else if (!di) { 145 /* Shouldn't happen but just in case... */ 146 btrfs_release_path(path); 147 goto again; 148 } 149 150 ret = btrfs_delete_one_dir_name(trans, root, path, di); 151 if (ret) 152 goto out; 153 154 /* 155 * We have a value to set, so go back and try to insert it now. 156 */ 157 if (value) { 158 btrfs_release_path(path); 159 goto again; 160 } 161 } 162 out: 163 btrfs_free_path(path); 164 return ret; 165 } 166 167 /* 168 * @value: "" makes the attribute to empty, NULL removes it 169 */ 170 int __btrfs_setxattr(struct btrfs_trans_handle *trans, 171 struct inode *inode, const char *name, 172 const void *value, size_t size, int flags) 173 { 174 struct btrfs_root *root = BTRFS_I(inode)->root; 175 int ret; 176 177 if (trans) 178 return do_setxattr(trans, inode, name, value, size, flags); 179 180 trans = btrfs_start_transaction(root, 2); 181 if (IS_ERR(trans)) 182 return PTR_ERR(trans); 183 184 ret = do_setxattr(trans, inode, name, value, size, flags); 185 if (ret) 186 goto out; 187 188 inode->i_ctime = CURRENT_TIME; 189 ret = btrfs_update_inode(trans, root, inode); 190 BUG_ON(ret); 191 out: 192 btrfs_end_transaction_throttle(trans, root); 193 return ret; 194 } 195 196 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 197 { 198 struct btrfs_key key, found_key; 199 struct inode *inode = dentry->d_inode; 200 struct btrfs_root *root = BTRFS_I(inode)->root; 201 struct btrfs_path *path; 202 struct extent_buffer *leaf; 203 struct btrfs_dir_item *di; 204 int ret = 0, slot; 205 size_t total_size = 0, size_left = size; 206 unsigned long name_ptr; 207 size_t name_len; 208 209 /* 210 * ok we want all objects associated with this id. 211 * NOTE: we set key.offset = 0; because we want to start with the 212 * first xattr that we find and walk forward 213 */ 214 key.objectid = btrfs_ino(inode); 215 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 216 key.offset = 0; 217 218 path = btrfs_alloc_path(); 219 if (!path) 220 return -ENOMEM; 221 path->reada = 2; 222 223 /* search for our xattrs */ 224 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 225 if (ret < 0) 226 goto err; 227 228 while (1) { 229 leaf = path->nodes[0]; 230 slot = path->slots[0]; 231 232 /* this is where we start walking through the path */ 233 if (slot >= btrfs_header_nritems(leaf)) { 234 /* 235 * if we've reached the last slot in this leaf we need 236 * to go to the next leaf and reset everything 237 */ 238 ret = btrfs_next_leaf(root, path); 239 if (ret < 0) 240 goto err; 241 else if (ret > 0) 242 break; 243 continue; 244 } 245 246 btrfs_item_key_to_cpu(leaf, &found_key, slot); 247 248 /* check to make sure this item is what we want */ 249 if (found_key.objectid != key.objectid) 250 break; 251 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 252 break; 253 254 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 255 if (verify_dir_item(root, leaf, di)) 256 continue; 257 258 name_len = btrfs_dir_name_len(leaf, di); 259 total_size += name_len + 1; 260 261 /* we are just looking for how big our buffer needs to be */ 262 if (!size) 263 goto next; 264 265 if (!buffer || (name_len + 1) > size_left) { 266 ret = -ERANGE; 267 goto err; 268 } 269 270 name_ptr = (unsigned long)(di + 1); 271 read_extent_buffer(leaf, buffer, name_ptr, name_len); 272 buffer[name_len] = '\0'; 273 274 size_left -= name_len + 1; 275 buffer += name_len + 1; 276 next: 277 path->slots[0]++; 278 } 279 ret = total_size; 280 281 err: 282 btrfs_free_path(path); 283 284 return ret; 285 } 286 287 /* 288 * List of handlers for synthetic system.* attributes. All real ondisk 289 * attributes are handled directly. 290 */ 291 const struct xattr_handler *btrfs_xattr_handlers[] = { 292 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 293 &btrfs_xattr_acl_access_handler, 294 &btrfs_xattr_acl_default_handler, 295 #endif 296 NULL, 297 }; 298 299 /* 300 * Check if the attribute is in a supported namespace. 301 * 302 * This applied after the check for the synthetic attributes in the system 303 * namespace. 304 */ 305 static bool btrfs_is_valid_xattr(const char *name) 306 { 307 return !strncmp(name, XATTR_SECURITY_PREFIX, 308 XATTR_SECURITY_PREFIX_LEN) || 309 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 310 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 311 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); 312 } 313 314 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 315 void *buffer, size_t size) 316 { 317 /* 318 * If this is a request for a synthetic attribute in the system.* 319 * namespace use the generic infrastructure to resolve a handler 320 * for it via sb->s_xattr. 321 */ 322 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 323 return generic_getxattr(dentry, name, buffer, size); 324 325 if (!btrfs_is_valid_xattr(name)) 326 return -EOPNOTSUPP; 327 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 328 } 329 330 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 331 size_t size, int flags) 332 { 333 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 334 335 /* 336 * The permission on security.* and system.* is not checked 337 * in permission(). 338 */ 339 if (btrfs_root_readonly(root)) 340 return -EROFS; 341 342 /* 343 * If this is a request for a synthetic attribute in the system.* 344 * namespace use the generic infrastructure to resolve a handler 345 * for it via sb->s_xattr. 346 */ 347 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 348 return generic_setxattr(dentry, name, value, size, flags); 349 350 if (!btrfs_is_valid_xattr(name)) 351 return -EOPNOTSUPP; 352 353 if (size == 0) 354 value = ""; /* empty EA, do not remove */ 355 356 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 357 flags); 358 } 359 360 int btrfs_removexattr(struct dentry *dentry, const char *name) 361 { 362 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 363 364 /* 365 * The permission on security.* and system.* is not checked 366 * in permission(). 367 */ 368 if (btrfs_root_readonly(root)) 369 return -EROFS; 370 371 /* 372 * If this is a request for a synthetic attribute in the system.* 373 * namespace use the generic infrastructure to resolve a handler 374 * for it via sb->s_xattr. 375 */ 376 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 377 return generic_removexattr(dentry, name); 378 379 if (!btrfs_is_valid_xattr(name)) 380 return -EOPNOTSUPP; 381 382 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 383 XATTR_REPLACE); 384 } 385 386 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 387 struct inode *inode, struct inode *dir, 388 const struct qstr *qstr) 389 { 390 int err; 391 size_t len; 392 void *value; 393 char *suffix; 394 char *name; 395 396 err = security_inode_init_security(inode, dir, qstr, &suffix, &value, 397 &len); 398 if (err) { 399 if (err == -EOPNOTSUPP) 400 return 0; 401 return err; 402 } 403 404 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1, 405 GFP_NOFS); 406 if (!name) { 407 err = -ENOMEM; 408 } else { 409 strcpy(name, XATTR_SECURITY_PREFIX); 410 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix); 411 err = __btrfs_setxattr(trans, inode, name, value, len, 0); 412 kfree(name); 413 } 414 415 kfree(suffix); 416 kfree(value); 417 return err; 418 } 419